Lighting control and power supply integrated circuits (ICs) are in common use in both electronic systems and in replaceable consumer lighting devices, e.g., light-emitting-diode (LED) and compact fluorescent lamp (CFL) replacements for traditional incandescent light bulbs.
In particular, in dimmable replacement light bulbs, matching the hue/intensity profile of a traditional incandescent bulb as the lighting is typically not performed. Separate LED strings of different colors are needed in order to change the hue of the light, which raises cost. Further, each LED string typically requires a separate controllable power supply, adding additional cost, in particular when isolation is required.
Therefore, it would be desirable to provide a lower-cost power source circuit that can supply multiple strings of LEDs without requiring separate power supplies.